1. Field of the Invention
The present invention relates to an apparatus provided with backup power supply for power supply which is supplied generally such as commercial power supply, a power controller that controls power of the apparatus, a program for controlling power, and a method for controlling power.
2. Description of Related Art
Conventionally, apparatuses for processing electronic data such as information processing apparatuses are provided with a backup power supply such as a UPS so as to prevent processed data from being lost or avoid malfunction during operation due to shutoff of power supply or temporary blackout.
Such an apparatus monitors the state of voltage, current, etc. of a general power supply (AC input power supply) (step S51), and in the case where the voltage value becomes less than a stipulated voltage value (V1) being a threshold value (step S52, Y), and when it is determined that the state with the voltage value less than the stipulated voltage value continues for a preset period of time or longer (step S53, Y), the power supply is switched to a backup power supply (step S54), as shown in FIG. 7 indicative of one example of the operation. Thus, at the time of power failure or temporary blackout of the power supply, operation of the apparatus can be maintained. In this case, the preset period of time is a short period of time during which stored electricity by a capacitor or the like can be used. There is a case in which the power supply is switched to a backup power supply immediately after the power supply voltage becomes less than the stipulated voltage value.
In the conventional technique, as described above, in case the power supply voltage becomes less than a threshold value, or the state with the voltage value less than the threshold value continues for a preset period of time or longer, the power supply is switched to a uniformly determined backup power supply, and the processing thereof is subjected to a uniquely set process.
On the other hand, in the case where backup power supplies of large and small electric capacities are installed, efficient operation of the apparatus can be maintained by making full use of these various backup power supplies depending on patterns of the power failure.
For example, when an apparatus is immediately restored from the power failure state to the normal state, it is desired that the apparatus be operated under the normal state using a backup power supply having large electric capacity which can drive the entire apparatus. On the other hand, when an apparatus is not immediately restored from the power failure state and the apparatus cannot be backed up even though a backup power supply having large electric capacity is used, it is necessary to save important electronic data immediately before shut down of the apparatus. In this case, a backup power supply having small electric capacity is used to perform such an important processing, which makes the operation of the apparatus reliable.
However, in the conventional technique, various backup power supplies are not properly used depending on patterns of the power failure, which cannot maintain efficient operation of the apparatus at the time of power failure. Furthermore, installing a backup power supply having large electric capacity on all apparatuses is not appropriate in view of cost and importance of operation state of the apparatus.
Furthermore, there are many patterns of the power failure or temporary blackout. For example, when temporary power failures often arise and a backup power supply is repeatedly used before being fully charged, stored electricity of the backup power supply is lower than that of the initial state. In this case, when the backup power supply is used similarly as the case of the initial power failure, operation of the apparatus cannot be maintained sufficiently.